1. Field of the Invention
The present invention relates to a remote control system, and more particularly, to an improved remote control system for controlling the operation of a base station having a transmitter operable on a plurality of radio channels.
2. Description of the Prior Art
Remote control systems for a base station have typically been architectured according to one of the following three configurations. First, a local control configuration may be provided by merely separating by a few feet a control station from a base station and providing a rather large amount of electrical interconnections. Due to the complexity and susceptibility to interference of the electrical interconnections, the control station may not be much further than 100 feet from the base station in the local control configuration.
Secondly, a direct-current control configuration may be provided where a control station applies predetermined amounts of current to a wire line for controlling various functions of a base station. The direct-current control configuration is limited to a range of approximately twenty miles simply because of the resistance of the wire line and the current levels necessary for operation. In addition, the direct-current configuration necessitates relatively large DC voltages to maintain the predetermined amounts of current in long wire lines having high loop resistances.
Finally, a tone control configuration may be provided where a control station applies different tones to a wire line for controlling the various functions of the base station. The tone control configuration, as illustrated in U.S. Pat. No. 3,577,080, can reliably operate over great distances, for example, the control station and the base station may be separated by several hundred miles. However, the tone control configuration necessitates relatively complex and costly control circuitry.
In all three of the foregoing configurations, multiple control units cannot be accommodated or added without substantial and costly redesign. Neither the direct-current control configuration nor the local control configuration provides a relatively inexpensive remote control system that has both the capacity to control many functions and a range of up to several miles.
For the foregoing and other shortcomings and problems, there has been a long felt need for an improved remote control system for controlling the operation of a remote base station.